64GB Kit (2 x 32GB) DDR4-2933 PC4-23400 Non-ECC Unbuffered Desktop Memory by NEMIX RAM at Amazon.com
4GB 1600MHZ SODIMM Single Rank at Amazon.com
OWC 32GB (2 x 16GB) PC21300 DDR4 2666MHz SO-DIMMs Memory, Compatible with Mac Mini 2018, iMac 2019 and up, and Compatible PCs, (OWC2666DDR4S32P) at Amazon.com